Building LCC considering building energy efficient elements

The following sensitivity analysis focuses on the use of building energy efficient elements. As argued by company A, the adoption of elements such as roof and wall insulations, cross ventilation, double clear glazing, well oriented house as well as the use of window overhangs the actual energy consumption can be reduced significantly while providing the house occupants with the required indoor comfort. Furthermore, they claim that the use of these elements eliminates or reduce significantly the need for critical appliances such as electric heater and air conditioning, respectively. Despite the existence of other energy efficiency strategies that can be adopted while promoting an energy efficient building (some of them have been discussed within this thesis) only elements suggested by companies A, B and D are considered in this discussion. The energy efficient design suggested by company A is presented in Appendix H, which indicates the house plan for types 2 and 3. In Appendices 5 and 6, the relative investment costs estimated by company B are indicated. Table 4.14 illustrates the total energy consumption of the type 2 and 3 houses when appliances operational time is adjusted, without taking into account the use of energy efficient appliances. However, adjustment of appliances operational time were considered, for instance, the surveyed houses on average kept their lights on for 9 hours, however considering energy efficient practices, the suggested time by company A, is of 5 hours. The use of electric heaters was eliminated, mostly because the Mozambican weather condition allows this elimination, considering that the houses are well oriented and insulated, as indicated by company A.

The running time ratio for freezers and refrigerators was determined according to the findings from the study carried out by Homes and Melo (2009). They concluded that the runtime of these appliances when controls for thermostat and damper are at maximum level is a factor of 0.66. This means that these appliances run for about 66% of the day 16 hours per day. This factor was used to correct the data from the survey, because almost all respondents indicated that refrigerators and freezers run for 24 hours, which is not the case. The same factor was also used for the proposed energy efficient houses.

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The study considered the maximum factor because Mozambique is a hot and humid country which makes these appliances to run for longer periods when compared to cold environments. Borges et al. (2011) state that, the runtime ratio for a refrigerator under 32˚C ambient temperature is about 50%, and when the temperature drops to 25˚C the runtime ratio is lower, and can reach 38%. Factors such as door opening, defrost strategies and internal loads also contribute to the optimum runtime ratio (Saidur et al., 2002 and Borges et al., 2011). The level of influence of each of these factors varies according to each situation and is difficult to capture, which justifies the use of the maximum ratio for this research.

Moreover, in the case of electric geysers, it was found that the respondents tried to estimate the real runtime, which is why the average runtime ratio for this appliance was about 13 hours. However, for the LCC calculation for the proposed energy efficient house, the average runtime was adjusted, from the previous 13 hours per day to 2 hours per day, as suggested by Company A. Company A also indicated that the use of air conditioning and fans, could be adjusted taking into account that on average the summer season lasts for 8 months in Mozambique, households could still use these devices for at least 5 hours a day starting from the middle of September until the middle April. Table 4.14 indicates that when the afore-mentioned adjustments are considered, the total consumption of energy reduces by 16% and 54% for type 2 and type 3 houses, respectively.

66 Table 4.13: Annual energy consumption of the type 2 and 3 houses including adjustments over the operational time,

without considering the use of energy efficient appliances.

Type of appliances D1* D2* D3* (W) D4* (W) D5* (h) D6* (h) D7* (W/h) D8* (W/h) Freezers 1 1 378 300 _{16 16 6,048 4,800} CFL 11 12 39 32 _{9 5 2,145 1,920} Incandescent 0 0 0 0 _{0 0 0 0} Televisions 2 3 196 166 _{9 9 3,528 4,482} Electric Geysers 1 1 1,653 2,357 _{13 2 3,306 4,714} Stoves 1 1 1,757 2,945 _{3 3 5,271 8,835} Kettles 1 1 1,526 1,513 _{1 1 1,526 1,513} Ironing Machine 1 1 1,162 1,142 _{1 1 1,162 1,142} DVD 1 1 48 38 _{3 3 144 114} Air conditioning 1 2 1,703 1,699 _{8 3 5,109 10,194} Fans 2 2 120 102 _{6 3 720 612} Microwave 1 1 1,411 1,261 _{1 1 1,411 1,261} Refrigerator 1 1 414 581 _{16 16 6,624 9,296} Sound amplifiers 1 1 52 96 _{4 4 208 384} Radios 1 1 49 67 _{4 4 196 268} Space heaters 1 1 1,370 2,175 _{1 0 0 0} Other appliances Computers 1 1 513 419 _{4 4 2,052 1,676} Toasters 1 1 505 723 _{3 3 1,515 2,169} Total W/h/day 40,965 53,380 Total kWh/year 14,747 19,217

*Note: D1=Number of appliances in a type 2 house, D2=Number of appliances in a type 3 house, D3= Average of the appliances power capacity in a type 2 house, D4=Average of the appliances power capacity in a type 3 house, D5=Average of the time that the appliances remain operational in both types of houses, D6=Suggested time to keep the appliances operational, D7=Total Energy consumed by the appliances in Watt hour – For the type 2 houses , D8=Total Energy consumed by the appliances in Watt hour – For the type 3 houses.

Table 4.15 indicates the LCC of the type 2 and 3 energy efficient houses considering that energy efficient elements are incorporated while developing the house. The initial investment for acquiring the house is surprisingly about 2,134,458.25MT, which is approximately 5% cheaper than the actual cost of buying one of the types 2 surveyed houses. It was also found that the initial investment cost of the type 3 energy efficient designs to be lower than the cost of acquiring similar house in Maputo city, which was around 11% lower compared to those which do not incorporate energy efficient measures (See more details in Appendix I).

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Many reasons account for this situation, for example there is the issue of price speculation, which in this case could be explained by the fact that the targeted area is located in the central city of Maputo, where there is a great demand for houses. Nevertheless, the findings clearly indicate potential savings not only with the annual energy consumption but also in the initial investment.Consequently, the LCC for the equivalent type 3 house that incorporates energy efficient measures is 5% lower than that of type 3 house, contrary, the LCC of the type 2 houses is nearly 1.5% higher than that of a type 2 house. .The relative minor savings is due to the fact that there are minor differences in the required amount for the initial investment in both situations.

Table 4.14 : LCC for type 2 and 3 houses that are energy efficient, without considering the use of energy efficient appliances.

Item Description of cost Present Value of Type 2

House (MT)

Present Value of Type 3 House

(MT) 1 Total Initial Investment (house and appliances) 2,255,624.25 3,394,359.50

2 Total cost for appliances replacement 5,153,761.29 6,252,603.12

3 Operating costs for the first 6 years 266,399.53 336,837.21

4 Operating costs, for the remaining 44 years 771,248.35 974,740.18

5 Maintenance costs 573,683.87 872,801.23

6 Residual Value (1,399.05) (2,128.51)

7 Total LCC in MT 9,019,318.24 11,829,212.71